Ease and comfort of pre-oxygenation with high-flow nasal oxygen cannulae vs. facemask: a randomised controlled trial.

The Difficult Airway Society recommends that all patients should be pre-oxygenated before the induction of general anaesthesia, but this may not always be easy or comfortable and anaesthesia may often be induced without full pre-oxygenation. We tested the hypothesis that high-flow nasal oxygen cannulae would be easier and more comfortable than facemasks for pre-oxygenation. We randomly allocated 199 patients undergoing elective surgery aged ≥ 10 years to pre-oxygenation using either high-flow nasal oxygen or facemask. Ease and comfort were assessed by anaesthetists and patients on 10-cm visual analogue scale and six-point smiley face scale, respectively. Secondary endpoints included end-tidal oxygen fraction after securing a definitive airway and time to secure an airway. A mean difference (95%CI) between groups in ratings of -0.76 (-1.25 to -0.27) cm for ease of use (p = 0.003) and -0.45 (-0.75 to -0.13) points for comfort (p = 0.006), both favoured high-flow nasal oxygen. A mean difference (95%CI) between groups in end-tidal oxygen fraction of 3.89% (2.41-5.37%) after securing a definitive airway also favoured high-flow nasal oxygen (p < 0.001). There was no significant difference between groups in the number of patients with hypoxaemia (Sp O2 < 90%) or severe hypoxaemia (Sp O2 < 85%) lasting ≥ 1 min or ≥ 2 min; in the proportion of patients with an end-tidal oxygen fraction < 87% in the first 5 min after tracheal intubation (52.2% vs. 58.9% in facemask and high-flow nasal oxygen groups, respectively; p = 0.31); or in time taken to secure an airway (11.6 vs. 12.2 min in facemask and high-flow nasal oxygen groups, respectively; p = 0.65). In conclusion, we found pre-oxygenation with high-flow nasal oxygen to be easier for anaesthetists and more comfortable for patients than pre-oxygenation with a facemask, with no clinically relevant differences in end-tidal oxygen fraction after securing a definitive airway or time to secure an airway. The differences in ease and comfort were modest.

A retrospective audit of postoperative days alive and out of hospital, including before and after implementation of the WHO surgical safety checklist.

We implemented the World Health Organization surgical safety checklist at Auckland City Hospital from November 2007. We hypothesised that the checklist would reduce postoperative mortality and increase days alive and out of hospital, both measured to 90 postoperative days. We compared outcomes for cohorts who had surgery during 18-month periods before vs. after checklist implementation. We also analysed outcomes during 9 years that included these periods (July 2004-December 2013). We analysed 9475 patients in the 18-month period before the checklist and 10,589 afterwards. We analysed 57,577 patients who had surgery from 2004 to 2013. Mean number of days alive and out of hospital (95%CI) in the cohort after checklist implementation was 1.0 (0.4-1.6) days longer than in the cohort preceding implementation, p < 0.001. Ninety-day mortality was 395/9475 (4%) and 362/10,589 (3%) in the cohorts before and after checklist implementation, multivariable odds ratio (95%CI) 0.93 (0.80-1.09), p = 0.4. The cohort changes in these outcomes were indistinguishable from longer-term trends in mortality and days alive and out of hospital observed during 9 years, as determined by Bayesian changepoint analysis. Postoperative mortality to 90 days was 228/5686 (4.0%) for Maori and 2047/51,921 (3.9%) for non-Maori, multivariable odds ratio (95%CI) 0.85 (0.73-0.99), p = 0.04. Maori spent on average (95%CI) 1.1 (0.5-1.7) fewer days alive and out of hospital than non-Maori, p < 0.001. In conclusion, our patients experienced improving postoperative outcomes from 2004 to 2013, including the periods before and after implementation of the surgical checklist. Maori patients had worse outcomes than non-Maori.

National risk prediction model for perioperative mortality in non-cardiac surgery.

BACKGROUND: Many multivariable models to calculate mortality risk after surgery are limited by insufficient sample size at development or by application to cohorts distinct from derivation populations. The aims of this study were to validate the Surgical Outcome Risk Tool (SORT) for a New Zealand population and to develop an extended NZRISK model to calculate 1-month, 1-year and 2-year mortality after non-cardiac surgery. METHODS: Data from the New Zealand National Minimum Data Set for patients having surgery between January 2013 and December 2014 were used to validate SORT. A random 75 per cent split of the data was used to develop the NZRISK model, which was validated in the other 25 per cent of the data set. RESULTS: External validation of SORT in the 360 140 patients who underwent surgery in the study period showed good discrimination (area under the receiver operating characteristic curve (AUROC) value of 0·906) but poor calibration (McFadden's pseudo-R2 0·137, calibration slope 5·32), indicating it was invalid in this national surgical population. Internal validation of the NZRISK model, which incorporates sex and ethnicity in addition to the variables used in SORT for 1-month, 1-year and 2-year outcomes, demonstrated excellent discrimination with AUROC values of 0·921, 0·904 and 0·895 respectively, and excellent calibration (McFadden's pseudo-R2 0·275, 0·308 and 0·312 respectively). Calibration slopes were 1·12, 1·02 and 1·02 respectively. CONCLUSION: The SORT performed poorly in this national population. However, inclusion of sex and ethnicity in the NZRISK model improved performance. Calculation of mortality risk beyond 30 days after surgery adds to the utility of this tool for shared decision-making.

ANTECEDENTES: Muchos modelos multivariados de estimación del riesgo de mortalidad después de la cirugía están limitados por haberse desarrollado a partir de tamaños muestrales insuficientes o por haberse aplicados a cohortes distintas de las poblaciones de derivación. Los objetivos de este estudio fueron validar el Surgical Outcome Risk Tool (SORT) para una población de Nueva Zelanda y desarrollar un modelo NZRISK extendido para calcular la mortalidad al mes y a los 1 y 2 años de una cirugía no cardíaca. MÉTODOS: Para validar el SORT se utilizó el Conjunto Mínimo Básico de Datos de Nueva Zelanda para los pacientes sometidos a cirugía entre enero de 2013 y diciembre de 2014. Se realizó una división aleatoria del 75% de los datos para desarrollar el modelo NZRISK que, posteriormente, se validó en el otro 25% del conjunto de datos. RESULTADOS: La validación externa de SORT en 360.140 pacientes intervenidos en el periodo analizado mostró una buena discriminación (área bajo las curvas de característica operativa del receptor (area under the receiver-operator characteristic curves (AUROC) 0,906)) pero con una mala calibración (pseudo-R2 de McFaddens 0,137 y pendiente de calibración 5,32), lo que indicaba que SORT no era válido para esta población quirúrgica nacional. La validación interna del modelo NZRISK, que incorpora el género y la etnia además de las variables utilizadas en el SORT, para los resultados al mes y a los 1 y 2 años demostró una excelente capacidad de discriminación con una AUROC de 0,921, 0,904, 0,895 respectivamente y una calibración excelente, con una pseudo-R2 de McFaddens de 0,275, 0,308 y 0,312 respectivamente. Las pendientes de calibración fueron de 1,12, 1,02 y 1,02, respectivamente. CONCLUSIÓN: El SORT no fue útil en esta población nacional. Sin embargo, la inclusión del género y la etnia en el modelo NZRISK mejoró sus resultados. El cálculo del riesgo de mortalidad más allá de 30 días después de la cirugía añade utilidad a esta herramienta para la toma de decisiones compartida.

Haemodynamic profiles of etomidate vs propofol for induction of anaesthesia: a randomised controlled trial in patients undergoing cardiac surgery.

BACKGROUND: Etomidate is frequently selected over propofol for induction of anaesthesia because of a putatively favourable haemodynamic profile, but data confirming this perception are limited. METHODS: Patients undergoing cardiac surgery were randomised to induction of anaesthesia with propofol or etomidate. Phase I (n=75) was conducted as open-label, whereas Phase II (n=75) was double blind. Mean arterial blood pressure (MAP) and boluses of vasopressor administered after induction were recorded. The primary endpoint was the area under the curve below baseline MAP (MAP-time integral) during the 10 min after induction. Secondary endpoints were the use of vasopressors over the same period, and the effect of blinding on the aforementioned endpoints. Groups were compared using regression models with phase and anaesthetist as factors. RESULTS: The mean difference between etomidate and propofol in the MAP-time integral below baseline was 2244 mm Hg s (95% confidence interval, 581-3906; P=0.009), representing a 34% greater reduction with propofol. Overall, vasopressors were used in 10/75 patients in the etomidate group vs 21/75 in the propofol group (P=0.38), and in 20/74 patients during the blinded phase vs 11/76 during the open-label phase (P=0.31). The interaction between randomisation and phase (open-labelled or blinded) was not significant for either primary (P=0.73) or secondary endpoints (P=0.90). CONCLUSIONS: Propofol caused a 34% greater reduction in MAP-time integral from baseline after induction of anaesthesia than etomidate, despite more frequent use of vasopressors with propofol, confirming the superior haemodynamic profile of etomidate in this context. The proportion of patients receiving vasopressors increased slightly, albeit not significantly, in both groups in the blinded phase. CLINICAL TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry, ACTRN12614000717651.

Facilitated self-reported anaesthetic medication errors before and after implementation of a safety bundle and barcode-based safety system.

BACKGROUND: Anaesthetic medication administration errors are a significant threat to patient safety. In 2002, we began collecting data about the rate and nature of anaesthetic medication errors and implemented a variety of measures to reduce errors. METHODS: Facilitated self-reporting of errors was carried out in 2002-2003. Subsequently, a medication safety bundle including 'smart' infusion pumps were implemented. During 2014 facilitated self-reporting commenced again. A barcode-based medication safety system was then implemented and the facilitated self-reporting was continued through 2015. RESULTS: During 2002-2003, a total of 11 709 paper forms were returned. There were 73 reports of errors (0.62% of anaesthetics) and 27 reports of intercepted errors (0.23%). During 2014, 14 572 computerised forms were completed. There were 57 reports of errors (0.39%) and 11 reports of intercepted errors (0.075%). Errors associated with medication infusions were reduced in comparison with those recorded in 2002-2003 (P<0.001). The rate of syringe swap error was also reduced (P=0.001). The reduction in error rate between 2002-2003 and 2014 was statistically significant (P=0.0076 and P=0.001 for errors and intercepted errors, respectively). From December 2014 through December 2015, 24 264 computerised forms were completed after implementation of a barcode-based medication safety system. There were 56 reports of errors (0.23%) and six reports of intercepted errors (0.025%). Vial swap errors in 2014-2015 were significantly reduced compared with those in 2014 (P=0.004). The reduction in error rate after implementation of the barcode-based medication safety system was statistically significant (P=0.0045 and P=0.021 for errors and intercepted errors, respectively). CONCLUSIONS: Reforms intended to reduce medication errors were associated with substantial improvement.

The incidence of hyperthermia during craniotomy.

There is evidence that even mild hyperthermia may exacerbate brain injury. There seem reasonable grounds for considering patients undergoing craniotomy as at risk for brain injury. A retrospective observational study was undertaken to measure the incidence of mild hyperthermia in craniotomy cases in which the patient was initially normothermic. Auckland City Hospital's database of electronic anaesthetic records was searched for adult patients who were normothermic (≤37°C) prior to undergoing craniotomy procedures. For each case, demographic data, intraoperative naso- or oropharyngeal temperature measurements, and paracetamol use were extracted. We identified the proportion of patients whose temperature rose to exceed normal (>37°C) and subdivided that group into the proportion in whom the temperature rose to ≥38°C. Two thousand, nine hundred and thirty-five craniotomy cases began their operations while normothermic and had adequate temperature data collected. There were 984 (33.5%) cases that had at least one temperature reading >37°C, for a mean (standard deviation [SD]) time of 66.0 (64.6) minutes, and 49 (1.7%) cases that had at least one reading ≥38°C for a mean (SD) time of 40.4 (38.1) minutes. The majority (77.8%) who became mildly hyperthermic remained so at the end of the procedure. New mild hyperthermia occurs commonly during craniotomy. In view of the compelling evidence of potential harm arising from mild hyperthermia in brain injury, these findings suggest an opportunity for practice improvement in the anaesthetic management of craniotomy patients. Reasonable steps should be taken by anaesthetists to avoid intraoperative hyperthermia of any degree.

Exploring performance of, and attitudes to, Stop- and Mock-Before-You-Block in preventing wrong-side blocks.

We conducted an online survey to assess the career experiences of wrong side blocks, the practice of Stop-Before-You-Block, the recently described method of Mock-Before-You-Block and attitudes to these. Respondents were 208 anaesthetists across nine hospitals (173 consultants or Staff and Associate Specialist doctors'), representing 3623 years of collective anaesthetic practice. There had been a total of 62 wrong side blocks (by 51 anaesthetists and one current trainee). Predisposing factors for this were commonly ascribed to distractions (35 (69%), for example due to rushing or teaching), patient positioning (9 (18%)) or miscommunication (6 (12%)). Two (4%) respondents felt they had performed Stop-Before-You-Block too early; 62 (41%) of all respondents stated they performed Stop-Before-You-Block as early as preparing the skin or on arrival of the patient in the anaesthetic room, and not any later. Twenty (10%) respondents admitted to not performing Stop-Before-You-Block at all or only occasionally (including 5 (2%) who had performed a wrong side block). Mock-Before-You-Block was easily understood (by 169 out of 197 (86%)) and 14 out of 61 (23%) respondents felt it would have prevented the wrong side error in their case. However, free-text comments indicated that many anaesthetists were reluctant to use a method that interrupted their performance of the block. We conclude that considerable work is needed to achieve full compliance with Stop-Before-You-Block at the correct time.

What are we injecting with our drugs?

In preparation for a case, an anaesthetist opened a 20 ml glass vial of propofol and aspirated the propofol into a syringe via a blunt drawing-up needle. Increased resistance was felt with aspiration. On inspection, a shard of glass was found at the tip of the drawing-up needle. The shard was presumed to be from the propofol ampoule, and to have fallen into the solution upon snapping open its glass tip. This illustrative case raises the issue of contamination of drugs by particles introduced during the drawing-up process. It also highlights the possibility that during the drawing-up process, intravenous drugs may become contaminated not just with particles, but with microorganisms on the surface of the particles. In this article, we discuss relevant recent research of the implications of this type of drug contamination. We draw attention to the need for meticulous care in drawing up and administering intravenous drugs during anaesthesia, particularly propofol.

Awareness during general anaesthesia in the first 4,000 incidents reported to webAIRS.

The aim of this study was to analyse the incidents related to awareness during general anaesthesia in the first 4,000 cases reported to webAIRS-an anaesthetic incident reporting system established in Australia and New Zealand in 2009. Included incidents were those in which the reporter selected "neurological" as the main category and "awareness/dreaming/nightmares" as a subcategory, those where the narrative report included the word "awareness" and those identified by the authors as possibly relevant to awareness. Sixty-one awareness-related incidents were analysed: 16 were classified as "awareness", 31 were classified as "no awareness but increased risk of awareness" and 14 were classified as "no awareness and no increased risk of awareness". Among 47 incidents in the former two categories, 42 (89%) were associated with low anaesthetic delivery and 24 (51%) were associated with signs of intraoperative wakefulness. Memory of intraoperative events caused significant ongoing distress for five of the 16 awareness patients. Patients continue to be put at risk of awareness by a range of well-described errors (such as syringe swaps) but also by some new errors related to recently introduced anaesthetic equipment, such as electronic anaesthesia workstations.

Patient and procedural factors associated with an increased risk of harm or death in the first 4,000 incidents reported to webAIRS.

This report describes an analysis of patient and procedural factors associated with a higher proportion of harm or death versus no harm in the first 4,000 incidents reported to webAIRS. The report is supplementary to a previous cross-sectional report on the first 4,000 incidents reported to webAIRS. The aim of this analysis was to identify potential patient or procedural factors that are more common in incidents resulting in harm or death than in incidents with more benign outcomes. There was a >50% higher proportion of harm (versus no harm) for incidents in which the patient's body mass index (BMI) was <18.5 kg/m2, for incidents in post-anaesthesia care units and non-theatre procedural areas, and for incidents under the main category of cardiovascular or neurological. The proportion of incidents associated with death was also higher (risk ratio >1.5) for BMI <18.5 kg/m2, incidents in non-theatre procedural areas, and incidents under the main category of cardiovascular or neurological. In addition, the proportion of incidents associated with death was higher for incidents in which the patient's age was >80 years, the American Society of Anesthesiologists physical status was 4 or 5, incidents involving non-elective procedures, and incidents occurring after hours (1800 to 0800 hours). When faced with incidents with these potential risk factors, anaesthetists should consider earlier interventions and request assistance at an earlier stage. Educational strategies on incident prevention and management should place even further emphasis on scenarios involving these factors.

A cross-sectional overview of the first 4,000 incidents reported to webAIRS, a de-identified web-based anaesthesia incident reporting system in Australia and New Zealand.

webAIRS is a web-based de-identified anaesthesia incident reporting system, which was introduced in Australia and New Zealand in September 2009. By July 2016, 4,000 incident reports had been received. The incidents covered a wide range of patient age (<28 days to >90 years), American Society of Anesthesiologists physical status, and body mass index (<18.5 to >50 kg/m2). They occurred across a wide range of anaesthesia techniques and grade of anaesthesia provider, and over a wide range of anaesthetising locations and times of day. In a high proportion the outcome was not benign; about 26% of incidents were associated with patient harm and a further 4% with death. Incidents appeared to be an ever-present risk in anaesthetic practice, with extrapolated estimates exceeding 200 per week across Australia and New Zealand. Independent of outcomes, many anaesthesia incidents were associated with increased use of health resources. The four most common main categories of incident were Respiratory/Airway, Medication, Cardiovascular, and Medical Device/Equipment. Over 50% of incidents were considered preventable. The narratives accompanying each incident provide a rich source of information, which will be analysed in subsequent reports on particular incident types. The summary data in this initial overview are a sober reminder of the prevalence and unpredictability of anaesthesia incidents, and their potential morbidity and mortality. The data justify current efforts to better prevent and manage anaesthesia incidents in Australia and New Zealand, and identify areas in which increased resources or additional initiatives may be required.

Bow-tie diagrams for risk management in anaesthesia.

Bow-tie analysis is a risk analysis and management tool that has been readily adopted into routine practice in many high reliability industries such as engineering, aviation and emergency services. However, it has received little exposure so far in healthcare. Nevertheless, its simplicity, versatility, and pictorial display may have benefits for the analysis of a range of healthcare risks, including complex and multiple risks and their interactions. Bow-tie diagrams are a combination of a fault tree and an event tree, which when combined take the shape of a bow tie. Central to bow-tie methodology is the concept of an undesired or 'Top Event', which occurs if a hazard progresses past all prevention controls. Top Events may also occasionally occur idiosyncratically. Irrespective of the cause of a Top Event, mitigation and recovery controls may influence the outcome. Hence the relationship of hazard to outcome can be viewed in one diagram along with possible causal sequences or accident trajectories. Potential uses for bow-tie diagrams in anaesthesia risk management include improved understanding of anaesthesia hazards and risks, pre-emptive identification of absent or inadequate hazard controls, investigation of clinical incidents, teaching anaesthesia risk management, and demonstrating risk management strategies to third parties when required.

Deviation from accepted drug administration guidelines during anaesthesia in twenty highly realistic simulated cases.

Deviations from accepted practice guidelines and protocols are poorly understood, yet some deviations are likely to be deliberate and carry potential for patient harm. Anaesthetic teams practice in a complex work environment and anaesthetists are unusual in that they both prescribe and administer the drugs they use, allowing scope for idiosyncratic practise. We aimed to better understand the intentions underlying deviation from accepted guidelines during drug administration in simulated cases. An observer recorded events that may have increased the risk of patient harm ('Events of Interest' [EOIs]) during 20 highly realistic simulated anaesthetic cases. In semi-structured interviews, details of EOIs were confirmed with participating anaesthetic teams, and intentions and reasoning underlying the confirmed deviations were discussed. Confirmed details of EOIs were tabulated and we undertook qualitative analysis of interview transcripts. Twenty-four EOIs (69% of 35 recorded) were judged by participants to carry potential for patient harm, and 12 (34%) were judged to be deviations from accepted guidelines (including one drug administration error). Underlying reasons for deviations included a strong sense of clinical autonomy, poor clinical relevance and a lack of evidence for guidelines, ingrained habits learnt in early training, and the influence of peers. Guidelines are important in clinical practice, yet self-identified deviation from accepted guidelines was common in our results, and all but one of these events was judged to carry potential for patient harm. A better understanding of the reasons underlying deviation from accepted guidelines is essential to the design of more effective guidelines and to achieving compliance.

Acute alcohol intoxication and bispectral index monitoring.

BACKGROUND: Bispectral index (BIS) monitoring is commonly used to decrease the risk of awareness during anaesthesia. We aimed to determine the relationship between blood alcohol concentration and brain function (as measured by BIS) in healthy adults. METHODS: In this prospective observational study, 21 anaesthetic registrars self-regulated alcohol consumption over a 3-h period. Expired alcohol concentration (breathalyser) and BIS measurements were performed hourly for 4 h. A venous blood alcohol sample was taken at the conclusion of the study period. RESULTS: The main outcome measures were the correlation between blood alcohol and brain function as measured by BIS and the change in BIS from baseline (∆BIS) at 4 h. The median number of standard drinks consumed was 9.1 (IQR 7.7-12.3), range 5.4-17. At 4 h, there was a moderate inverse correlation between BIS and blood alcohol (r = -0.49, P = 0.029) and between ∆BIS and blood alcohol (r = -0.46, P =0.043). CONCLUSION: In healthy young adults, we found a moderate correlation between venous blood alcohol concentration and BIS. This suggests that acute alcohol consumption can decrease BIS. This information may be relevant when providing anaesthesia to intoxicated patients who require urgent or time-critical surgery, although certain limitations of this study should be kept in mind.

A prospective, observational study of the effects of implementation strategy on compliance with a surgical safety checklist.

BACKGROUND: The reported benefits of using the WHO Surgical Safety Checklist (SSC) are likely to depend on compliance with its correct use. Compliance with SSC administration in centres that have introduced the checklist under a research protocol may differ from centres where the SSC is introduced independently. OBJECTIVE: To compare compliance with SSC administration at an original WHO pilot study centre (Hospital 1) with that at a similar neighbouring hospital (Hospital 2) that independently integrated the SSC with pre-existing practice. METHODS: This was a prospective, observational study. One hundred operations were observed at each hospital. We recorded: compliance with administration of SSC domains (Sign In, Time Out and Sign Out) and individual domain items; timing of domain administration; and operating room team engagement during administration. RESULTS: Domain compliance at Hospital 1 and Hospital 2, respectively, was: 96% and 31% (p<0.0005) for Sign In; 99% and 48% (p<0.0005) for Time Out and 22% and 9% (p=0.008) for Sign Out. Engagement of two or more teams during Sign In and Time Out occurred more frequently at Hospital 2 than at Hospital 1. DISCUSSION: Compliance with administration of SSC domains was lower at Hospital 2 which introduced the SSC outside the context of a strict study protocol. This finding mandates caution in extrapolation of benefits identified in SSC studies to non-study hospitals. Staff engagement was better at Hospital 2 where checklist administration leadership is strategically shared among anaesthetic, surgical and nursing team members as compared with exclusive nursing leadership at Hospital 1. STUDY REGISTRY NUMBER: Australian and New Zealand Clinical Trials Registry: Ref: ACTRN12612000135819, http://www.anzctr.org.au/trial_view.aspx?ID=362007.